An example of relatively large electrical machinery is an electrical generator driven by a turbine in a power generating plant. The electrical generator generally includes a rotor, and a stator surrounding the rotor. Stator windings or coils extend outwardly to the ends of the stator. The stator coil ends are connected to parallel phase rings at the end of the stator.
The size and configuration of an electrical generator generally requires that, to facilitate the installing or replacing of stator coils of the generator, the stator coils be arranged in physically separate coil sections, or halves. After they are set in their appropriate location, the stator coils need to be electrically and mechanically connected to one another at their ends. Similar connections may also be used between the ends of each phase coil. Maintaining consistently reliable series and phase connections between such coil ends is an important consideration both from a mechanical and an electrical standpoint.
It is known to use brazing techniques to affix connectors, such as made up of solid copper bars, to each coil end. This can provide effective series and phase connections between the coil ends. However, such techniques may be time-consuming and could take several days for performing a service rewind operation, even for experienced and skilled service personnel.
U.S. Pat. No. 4,894,575 to Nilsson et al. discloses an electrical generator connection to connect coil ends in series. A header cap having a spherically shaped end portion is brazed to each coil end to be connected. The spherically shaped end portion includes a top coil water hose nipple in the center thereof to allow fluid for cooling to pass therein. A pair of connector bars, each having similarly sized spherical seats, receives the spherically shaped portion of each coil end header cap. Electrical and mechanical connections are provided by bolting two connector bars together.
Similarly, PCT Publication No. WO2006/063186 discloses a bolted spherical series and phase connector for stator coils. A header cap having a spherically shaped end portion with a fluid port centrally located therein is brazed or connected to each stator coil to be connected. A pair of connector bars, each having similarly sized spherical seats, receives the spherically shaped portion of each coil end header cap. Electrical and mechanical connections are provided by bolting two connector bars together.
Still, the above connecting techniques may not be time-saving, especially when connecting a stator coil to a parallel ring in performing a service rewind operation. This time can be further extended for performing a rewind operation on a non-OEM generator, where an existing parallel ring is not positioned serially, or in a top-bottom configuration. In this case, the techniques already known do not apply, as they apply to a radial connection for stator coils. Thus, there is a need to reduce the time for performing such operations.